The present invention relates to an analog flow meter instrument and particularly to such an instrument for establishing an analog electrical signal linearly related to a fluid flow.
In various operating systems, the flow of a fluid is monitored on a continuous basis to insure appropriate functioning of the system. The flow may be monitored by a flow meter and provide a visual readout of the flow rate. The flow monitor or sensor may be connected into a control system to control the flow, or provide outputs indicative of the system condition including alarm conditions. In either system, the flow sensor may require mounting at the machine or some other remote location, with the signal transmitted to a remote control station. With modern day computer designs and the like, various digital monitors with digital transmission of the flow-related signals have been developed and operated satisfactorily in various environments. A typical digital system is shown in U.S. patent application "Linear Digital Flowmeter" with Ser. No. 06/669,090, now U.S. Pat. No. 4,774,676, filed by Stenzel et al and assigned to a common assignee with the present invention. Such systems are relatively complex and thereby costly. Although digital signals are readily transmitted over long lengths, extraneous signals may be induced into the signal line in various commercial installations.
There is therefore a need for a less costly system which will also provide for a reliable transmission of the flow meter signal over relatively long lines in a manufacturing and operating environment.